Op. Nagpal et al., WAVE CHARACTERISTICS IN THE TROPOSPHERE AND STRATOSPHERE OVER THE INDIAN TROPICS DURING THE DYANA PERIOD, Journal of atmospheric and terrestrial physics, 56(9), 1994, pp. 1117-1133
One of the important scientific objectives of the international DYANA
campaign was to obtain the characteristics of planetary scale waves in
the low-latitude middle atmosphere. India participated in this campai
gn by way of launching several rockets and high-altitude balloons from
a number of locations to determine the vertical structure of differen
t wave modes present during January-March 1990. Rocket launchings were
conducted from two stations, namely Thumba (8.5-degrees-N, 77.0-degre
es-E) with M-100 rockets and Balasore (21.5-degrees-N, 87.0-degrees-E)
with RH-200 rockets, while balloons were launched from three stations
, i.e. Trivandrum near Thumba, Minicoy (8.2-degrees-N, 73.0-degrees-E)
and Port Blair (11.7-degrees-N. 92.7-degrees-E). In addition. there w
ere balloon flights from Hyderabad (17.3-degrees-N, 78.3-degrees-E) an
d Bhubaneshwar (20.2-degrees-N, 85.5-degrees-E). The results of the sy
noptic scale wave activity as obtained from various data sources are g
iven here. Three prominent peaks with wave periods near 6 8 days (shor
t periods), 10-12 days (medium periods) and 30-45 days (long periods)
are found to occur at all the stations, The medium- and long-period wa
ves appear to be forced Rossby modes penetrating from midlatitudes whi
le short period waves all have characteristics matching those of mixed
Rossby-gravity waves. A very interesting result is the presence of lo
ng-period oscillations in the upper stratosphere and mesosphere, with
very large amplitude, contrary to earlier observations.